The critical Microsoft Windows and Office vulnerability that came to light two days ago is being more widely exploited than previously reported, making it more urgent that end users install a temporary fix right away.

Early research into the zero-day exploit detected only highly targeted attacks on individuals or companies that were mostly located in the Middle East and South Asia. More often than not, the word "targeted" is used to describe espionage campaigns aimed a particular company or industry. Now, researchers at two security firms have uncovered evidence that the same critical flaw—found in Windows Vista, Windows Server 2008, Microsoft Office 2003 through 2010, and all supported versions of Microsoft Lync—is also being targeted in wider-ranging hacking campaigns being carried out by multiple gangs, including one made up of financially motivated criminals.

The more recently discovered attacks are being carried out by the same India-based group behind Operation Hangover, a malware campaign first detected earlier this year, researchers from security firm FireEye wrote in a recent blog post. The researchers went on to say that the same attacks—which exploit weaknesses in the way Microsoft code processes TIFF images—is being waged by yet another group, alternately dubbed Arx and Ark, to deliver the Citadel trojan. Citadel is a highly malicious piece of malware that's mostlyused by criminals to access and liquidate online bank accounts...